The present invention concerns a proportional valve, especially for the shifting pressure regulation in an automatic transmission for a motor vehicle.
Proportional valves for the regulation of pressure are in manifold usage in automobile technology.
Pressure regulating valves, for example, are employed for the braking circuit for motor vehicles which are equipped with Anti-Blocking-System (ABS), as has been disclosed by DE 19715 024. In this cited patent, a shifting arrangement is described for the connection of current consuming equipment to an energy supply with emphasis given to a hydraulic pump and the electrically activated hydraulic valve of an ABS control arrangement for a motor vehicle. In this case, there is added, between the consuming equipment and the energy source, ON/OFF switching of the pump for individual activation of the hydraulic valve and for a total shutoff thereof.
Valves of the type used for the ABS-braking technology have been constructed also as digital valves, which have a magnetic interface available, so that a separation can be directly realized between the hydraulic and the electrical sections of the complete module in the digital valve. This entails the advantage, that with highly integrated modules, on the one hand separately testable units are made, and on the other hand by means of the high degree of integration, savings in cost become possible. This subdivision into hydraulic and electrical sections of a complete module has, up to this time, exclusively been adaptable for shift valve service, since, in this case, the manufacturing tolerances in the magnetic interface suffice to meet the requirements of the reproducibility of the magnetic flux.
The purpose of the present invention is to create a proportional valve, which, likewise, is divided by means of a magnetic interface into an electrical section and into a hydraulic section and in which the magnetic flux exhibits a high degree of reproducibility.
Starting from a proportional valve of the type described more closely in the introductory passages, the achievement of this purpose is accomplished by the features given in Claim 1. Advantageous embodiments are described in the subordinate claims.
Within the framework of the invention, provision has also been made, that the proportional valve, by means of a magnetic interface, is divided into a hydraulic section and an electrical section, whereby the bearing surfaces of the hydraulic valve spool are located on that end of the valve remote from the electrical coil, that is, the bearing surfaces are placed in the hydraulic section, so that the armature remains free in the coil space.
The magnetic interface is comprised of, first, a meandering line in the coil housing casing, which runs essentially perpendicular to the valve axis, second, a cross-slotting producing a spring action, and third, the said interface exhibits the shape of a slide fit with a lengthy transition taper.
Advantageously, the electrical section is provided with knife edge contacts and floats freely in a provided receiver with a bent shaped spring. The module possesses on its side which receives the electrical section a disk spring for transmitting externally imposed, axially directed forces against the magnetic interface.
With the invented design of a proportional valve, which is particularly well adapted for the shifting pressure regulation in automatic transmissions for motor vehicles, the advantage is achieved, that two separate, testable units have been made available, namely one being the electrical section and the other being the hydraulic section. The responsibility for a testable mechanical/electronic complete module can then be shifted to the suppliers. With the addition of further electrical functions, placement of this proportional valve is possible into the transfer plate furnished in the automatic transmission. A cost savings can be made by the omission of more specialized components. The integrated, compact construction design makes possible, in addition, an optimal use of installation space.